Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$10.34	8.800%	$11.2499	$11.25	$11.25	$11.20
Purchase #2	$11.48	6.626%	$12.2407	$12.24	$12.25	$12.20
Purchase #3	$81.83	12.636%	$92.17	$92.17	$92.15	$92.20
Purchase #4	$141.57	9.537%	$155.0715	$155.07	$155.05	$155.10
Purchase #5	$108.94	13.410%	$123.5489	$123.55	$123.55	$123.50
Purchase #6	$166.89	13.354%	$189.1765	$189.18	$189.20	$189.20
Purchase #7	$132.70	7.671%	$142.8794	$142.88	$142.90	$142.90
7 purchase totals =	$653.75		$726.3369	$726.34	$726.35	$726.30